/* mockturtle: C++ logic network library
 * Copyright (C) 2018-2019  EPFL
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

/*!
  \file storage.hpp
  \brief Configurable storage container

  \author Mathias Soeken
  \author Heinz Riener
*/

#pragma once

#include <array>
#include <iostream>
#include <unordered_map>
#include <vector>

#include <sparsepp/spp.h>

namespace mockturtle {

template <int PointerFieldSize = 0>
struct node_pointer {
  private:
    static constexpr auto _len = sizeof(uint64_t) * 8;

  public:
    node_pointer() = default;
    node_pointer(uint64_t index, uint64_t weight)
        : weight(weight), index(index) {}

    union {
        struct {
            uint64_t weight : PointerFieldSize;
            uint64_t index : _len - PointerFieldSize;
        };
        uint64_t data;
    };

    bool operator==(node_pointer<PointerFieldSize> const& other) const {
        return data == other.data;
    }
};

template <>
struct node_pointer<0> {
  public:
    node_pointer<0>() = default;
    node_pointer<0>(uint64_t index) : index(index) {}

    union {
        uint64_t index;
        uint64_t data;
    };

    bool operator==(node_pointer<0> const& other) const {
        return data == other.data;
    }
};

union cauint64_t {
    uint64_t n{0};
    struct {
        uint64_t h1 : 32;
        uint64_t h2 : 32;
    };
    struct {
        uint64_t q1 : 16;
        uint64_t q2 : 16;
        uint64_t q3 : 16;
        uint64_t q4 : 16;
    };
};

template <int Fanin, int Size = 0, int PointerFieldSize = 0>
struct regular_node {
    using pointer_type = node_pointer<PointerFieldSize>;

    std::array<pointer_type, Fanin> children;
    std::array<cauint64_t, Size> data;

    bool
    operator==(regular_node<Fanin, Size, PointerFieldSize> const& other) const {
        return children == other.children;
    }
};

template <int Size = 0, int PointerFieldSize = 0>
struct mixed_fanin_node {
    using pointer_type = node_pointer<PointerFieldSize>;

    std::vector<pointer_type> children;
    std::array<cauint64_t, Size> data;

    bool
    operator==(mixed_fanin_node<Size, PointerFieldSize> const& other) const {
        return children == other.children;
    }
};

/*! \brief Hash function for 64-bit word */
inline uint64_t hash_block(uint64_t word) {
    /* from boost::hash_detail::hash_value_unsigned */
    return word ^ (word + (word << 6) + (word >> 2));
}

/*! \brief Combines two hash values */
inline void hash_combine(uint64_t& seed, uint64_t other) {
    /* from boost::hash_detail::hash_combine_impl */
    const uint64_t m = UINT64_C(0xc6a4a7935bd1e995);
    const int r = 47;

    other *= m;
    other ^= other >> r;
    other *= m;

    seed ^= other;
    seed *= m;

    seed += 0xe6546b64;
}

template <typename Node>
struct node_hash {
    uint64_t operator()(const Node& n) const {
        if (n.children.size() == 0)
            return 0;

        auto it = std::begin(n.children);
        auto seed = hash_block(it->data);
        ++it;

        while (it != std::end(n.children)) {
            hash_combine(seed, hash_block(it->data));
            ++it;
        }

        return seed;
    }
};

struct empty_storage_data {};

template <typename Node, typename T = empty_storage_data,
          typename NodeHasher = node_hash<Node>>
struct storage {
    storage() {
        nodes.reserve(10000u);
        hash.reserve(10000u);
        hash.set_resizing_parameters(.4f, .95f);

        /* we generally reserve the first node for a constant */
        nodes.emplace_back();
    }

    using node_type = Node;

    std::vector<node_type> nodes;
    std::vector<uint64_t> inputs;
    std::vector<typename node_type::pointer_type> outputs;

    spp::sparse_hash_map<node_type, uint64_t, NodeHasher> hash;

    T data;
};

} /* namespace mockturtle */
